Extrusion laminating substrate with adhesive of olefin polymer and polyepoxide

ABSTRACT

An adhesive resin composition comprising: 
     (A) At least one component selected from the group consisting of (i) polyolefins having a melt flow rate of 0.1 to 30 g/10 min and (ii) olefinic polymers having at least one functional group capable of reacting with an epoxy group; and 
     (B) an epoxy compound having at least two epoxy groups in the molecule and having a number average molecular weight of 3000 or less, wherein the ratio of the component (B) to the total weight of the components (A) and (B) is 0.01 to 5% by weight, and a laminate of (a) a layer composed of the above-mentioned adhesive resin composition and a substrate contacted therewith.

This is a continuation of application Ser. No. 08/839,323, filed Apr.17, 1997, of which is a division of application Ser No. 08/535,889 filedSep. 28, 1995, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an adhesive resin composition havinghigh speed moldability, thin moldability, low neck-in property, highdraw-down property, excellent heat sensitive adhesion, and excellentcalendering and exhibiting strong adhesion properties with a substratecomposed of a polyester, polyamide, metal foil (e.g., aluminum foil),etc., in particular, a polyester, and also relates to a laminate havinga layer composed of the adhesive resin composition and a process forproducing the same. This laminate can be used as packaging such as foodpackaging.

2. Description of the Related Art

Polyolefins such as polyethylene are excellent in heat sealability andmoisture-proofing and is easy to extrude, and therefore, has been usedas a single layer film, sheet, or material for shaped containers andalso has been widely used in, for example, a packaging field as alaminate with various resin films and sheets, metal foils such asaluminum foil, paper, etc. However, polyolefins are inherently nonpolarand has the defect of poor adhesion to different materials, inparticular to polar materials such as polyamide, polyester, aluminumfoil. Accordingly, various methods have been proposed to form amultilayer laminate using polyolefins.

In order to produce a laminate of polyethylene and polyamide, forexample, the following methods using a modified polyolefin rather thanthe polyethylene alone have been utilized:

(1) The so-called co-extrusion method of melting a modified polyolefinobtained by graft polymerizing an unsaturated carboxylic acid or itsderivative onto polyolefin, an ethylene copolymer obtained bycopolymerizing ethylene and an unsaturated carboxylic acid or itsderivative, or a composition comprising these polymers and a polyolefinwith a polyamide resin and extruding the same from a die to obtain alaminate,

(2) The method of preparing a polyamide film in advance and extrusionlaminating (or coating) it with a blend of polyethylene and the abovepolymer,

(3) The method of co-extrusion laminating a polyolefin and the abovepolymer on a polyamide film.

Further, in order to produce a laminate of polyethylene and polyester,there has been proposed the method of using a polymer obtained bygrafting glycidyl methacrylate or allylglycidyl ether etc. onto apolyolefin or by copolymerization with ethylene and co-extruding with apolyester or co-extrusion laminating a substrate such as a polyesterfilm.

These methods, however, may give a bond strength in the case ofco-extrusion, but cannot give a sufficient bond strength in the case oflamination for laminating on a substrate such as a film, sheet, orpaper.

In particular, it is difficult to obtain a laminate having a strong bondstrength with, for example, a polyester based substrate.

In order to improve the bond strength, there is the method of raisingthe temperature at the time of formation, but the polymer is poor inheat stability and decomposes therefore, there is the problem of an odorand fumes at the time of formation. Further, there is the problem of anodor remaining in the laminate product.

As another method for improving the bond strength, there is the methodof applying a corona discharge to the substrate. However, in this case,it is necessary to separately prepare a special equipment(s). Also, thebond strength with the substrate is not sufficient.

Furthermore, in order to improve the adhesion, the ozone treatmentmethod of blowing ozone on the resin discharged from the die to causethe surface to oxidize has been used. The ozone treatment has theadvantage of enabling oxidation of just the surface requiring theadhesion at a low temperature (Japanese Unexamined Patent Publication(Kokai) No. 57-157724). However, ozone has the problems of odor,corrosiveness, etc. and is still limited in use. Furthermore, the levelof the bond strength is still insufficient. In particular, since thelaminate absorbs moisture, there is the problem of a large decline inthe bond strength.

As a reliable method for obtaining the sufficient adhesion propertieswith the substrate an adhesive known as an anchor coating agent (orprimer) is jointly used.

This method uses an adhesive layer interposed between the substrate andthe laminate resin. As the adhesive, an adhesive such as of the iminetype such as polyethylene imine or the urethane type is used. Ingeneral, a urethane type adhesive is widely used due to the high bondstrength thereof. However, in this method, while a high bond strength isobtained, the coating process is complicated. Further, an organicsolvent is used. Therefore, there are also problems in safety or theworking environment. Further, it is necessary to prepare the solution ofanchor coating agent and wipe off the anchor coating agent adhering tothe rolls, so there is the problem of a major reduction in the operationefficiency.

Furthermore, methods of introducing an acid anhydride group, carboxylgroup, etc. into the polyolefin are also proposed (see JapaneseUnexamined Patent Publication (Kokai) No. 57-133055, Japanese UnexaminedPatent Publication (Kokai) No. 59-75915, etc.). However, according tothese methods, the adhesion properties with a polyester are insufficientand it is impossible to directly bond to a polyester by extrusionlamination.

SUMMARY OF THE INVENTION

Accordingly, the objects of the present invention are to eliminate theabove-mentioned disadvantages of the conventional art and to provide anadhesive resin composition free from the above defects, having highspeed formability, thin formability, low neck-in property, highdraw-down property, excellent heat sensitive adhesion, and excellentcalendering and provided with strong adhesion properties with asubstrate comprising a polyester, polyamide, or aluminum foil, inparticular, a polyester, and a laminate having a layer composed of theadhesive resin composition.

Other objects and advantages of the present invention will be apparentfrom the following description.

In accordance with the present invention, there is provided an adhesiveresin composition comprising:

(A) at least one component selected from the group consisting of (i)polyolefins having a melt flow rate of 0.1 to 30 g/10 min and (ii)olefin polymers having at least one functional group capable of reactingwith an epoxy group; and

(B) an epoxy compound having at least two epoxy groups in the moleculeand having a number average molecular weight of 3000 or less, the ratioof the component (B) to the total weight of the components (A) and (B)being 0.01 to 5% by weight.

In accordance with the present invention, there is also provided alaminate comprising at least two layers of (a) a layer composed of anadhesive resin composition according to the present invention and (b) asubstrate directly contacted with said layer (a).

In accordance with the present invention, there is further provided aprocess for producing the laminate according to the present invention,wherein the laminate is produced by extrusion lamination, thermaladhesion or calendering.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be explained in further detail below.

The polyolefin usable as the component (A) (i) used in the presentinvention is a homopolymer or copolymer of ethylene or an α-olefin of 3to 16 carbon atoms. Examples of such a polyolefin are a branched lowdensity polyethylene (hereinafter referred to as "LDPE"), a linear lowdensity polyethylene (hereinafter referred to as "LLDPE"), medium andhigh density polyethylene (hereinafter referred to as "HDPE"), anethylene and vinyl acetate and/or methacrylate copolymer, propylenepolymer, etc. In particular, the use of LDPE is preferred.

These polyolefins may be used alone or in any mixtures thereof.

An LDPE can be generally obtained by effecting the polymerization at ahigh pressure of, for example, 1000 to 3500 atm. in the presence of afree-radical initiator such as a peroxide. It is characterized by thepossession of a large number of long-chain branches, and therefore, itis known that it maintains a superior extrudability. The reactor usedfor the polymerization may be any of an autoclave or tubular type.

An HDPE and LLDPE generally may be obtained by polymerizing ethylenealone or copolymerizing ethylene and an α-olefin having 3 to 16 carbonatoms using a catalyst known as a Ziegler catalyst, methallocenecatalyst, Phillips catalyst, etc. In general, these are produced by themedium and low pressure method, but may also be produced by the highpressure method and may further be produced by any method such as thegas phase method, solution method, slurry method, etc.

The copolymer of ethylene and vinyl acetate and/or methacrylate isgenerally obtained by effecting the polymerization in the presence of afree radical initiator such as a peroxide in the same way as an LDPE.

As the propylene polymer, a propylene polymer alone or a random or blockcopolymer of propylene and ethylene or an α-olefin having 4 to 16 carbonatoms may be used.

The melt flow rate of the polyolefin (according to JIS K 6758, showingthe value measured at 190° C. for polyethylene resins or at 230° C. forpolypropylene resins, hereinafter referred to as the "MFR") is 0.1 to 30g/10 minutes, preferably 1 to 15 g/10 minutes. When the MFR is less than0.1 g/10 minutes, the high speed formability and the thin formabilitybecome inferior. Contrary to this, when over 30 g/10 minutes, the heatseal strength and the neck-in characteristic are unpreferably decreased.

The olefin polymer having at least one functional group capable ofreacting with an epoxy group usable as the component (A)(ii) are thosehaving, for example, a carboxyl group or its derivative, an amino group,a phenol group, hydroxyl group, thiol group, etc. Among these, from theviewpoint of the balance between the reactivity and the stability, it ispreferable that there be at least one group selected from the groupconsisting of acid anhydride groups, carboxyl groups, and carboxylicacid metal salts (i.e., metal carboxylate) present in the molecule. Asthe method of introducing the functional group capable of reacting withthe epoxy groups, into the olefin polymer, the copolymerization methodand grafting method may be principally used. As the olefin, ethylene orolefins having a carbon atom of 3 to 16 may be preferably used.

As the olefin polymer having a functional group capable of reacting withan epoxy group produced by the copolymerization method, a multipolymerof ethylene and a compound copolymerizable with ethylene may bementioned.

As the compound copolymerizable with the ethylene for thecopolymerization, an α,β-unsaturated carboxylic acid such as(meth)acrylic acid, an α,β-unsaturated metal carboxylate such as sodium(meth)acrylate, zinc (meth)acrylate, an unsaturated carboxylic acidanhydride such as maleic anhydride, itaconic anhydride, and citraconicanhydride, a hydroxyl-group containing compound such as ahydroxyethylmethacrylate and methallylalcohol, an unsaturated aminecompound such as allylamine, etc. may be mentioned, but the invention isnot limited to these compounds.

Further, in addition to these unsaturated compounds, it is also possibleto copolymerize and use methacrylates, vinyl alcohol esters such asvinyl acetate and vinyl propionate, etc.

These compounds may be used in any mixture thereof in the copolymer withthe ethylene. Further, two or more types of the copolymers of thesecompounds and ethylene may be used together.

The polyolefin with the functional group capable of reacting with anepoxy group introduced by this graft modification generally is producedby contacting the polyolefin, a radical initiator, and a modifiyingcompound in a molten or solution state.

As the polyolefin for the graft modification, an LDPE, LLDPE, HDPE,polypropylene, propylene-ethylene copolymer, propylene-butene-1copolymer, ethylene-vinyl acetate copolymer, ethylene-methacrylatecopolymer, ethylene-vinyl acetate-methacrylate copolymer, etc. alone orin any mixture thereof may be mentioned. These polymers may be producedin any conventional monomer.

Further, it is also possible to use a further graft-modified copolymeralready including an acid or its derivative, such as anethylene-methacrylate-maleic anhydride copolymer.

The radical initiator usable in the present invention is notparticularly limited, but in general an organic peroxide is used. Amongthese, in view of the reactivity and easy handling, dicumyl peroxide,2,5-dimethyl-2,5-bis(t-butyl-peroxide)hexane,1,3-bis(2-t-butylperoxyisopropyl) benzene, and benzoylperoxide may beparticularly mentioned as specific useful examples.

As the unsaturated compound for the modification, an unsaturatedcompound similar to the compounds copolymerizable with ethylenementioned above can be used. Basically, any compounds having an acid orits anhydride group, its metal salt group, ester, amine group, hydroxylgroup, etc. and radical reactable unsaturated groups can be used.

As the unsaturated compound for the modification, an unsaturatedcarboxylic acid such as methacrylic acid, an unsaturated metalcarboxylate such as sodium methacrylate, an unsaturated carboxylic acidanhydride such as maleic anhydride, itaconic anhydride, and citraconicanhydride, an unsaturated hydroxyl group containing compound such ashydroxyethyl methacrylate and methallyalcohol, an unsaturated aminecompound such as allylamine, etc. may be mentioned, but the invention isnot limited to these compounds.

The content of the functional groups in the polyolefin resin of thepresent invention is 0.05 to 20% by weight, preferably 0.1 to 10% byweight, particularly preferably 0.2 to 5% by weight, based on the weightof the modified monomer.

Specific examples of the polyolefin resin of the present invention arean ethylene-maleic anhydride copolymer, ethylene-itaconic anhydridecopolymer, ethylene-citraconic anhydride copolymer,ethylene-methacrylate copolymer, ethylene-sodium methacrylate copolymer,ethylene-maleic anhydride-methacrylate copolymer, ethylene-maleicanhydride-vinyl alcohol ester copolymer, maleic anhydride-modifiedpolyethylene, maleic anhydride-modified polypropylene, maleicanhydride-modified polyethylene, maleic anhydride-modifiedpolypropylene, maleic anhydride-modified ethylene-methacrylatecopolymer. Among these, the use of an ethylene-maleic anhydridecopolymer and ethylene-maleic anhydride-methacrylate copolymer ispreferable.

The amount of the component (A) (ii), i.e., the olefin polymer having afunctional group capable of reacting with an epoxy group, is generallyless than 30% by weight, preferably 2 to 25% by weight, more preferably5 to 20% by weight, based upon the total amount of the component(A)+component (B).

The addition of the component (A)(ii) can further improve the adhesionproperty.

The epoxy compound usable as the component (B) in the present inventionis an epoxy compound having a molecular weight of not more than 3000 andcontaining at least two epoxy groups (or oxirane groups) in themolecule.

The epoxy compound must include at least two epoxy groups (or oxiranegroups) in the molecule. When only one epoxy group is included in themolecule, there is no substantial effect on the adhesion properties withthe substrate intended by the present invention.

The molecular weight of the epoxy compound must be no more than 3000,preferably no more than 1500, and more preferably 200 to 1500. When themolecular weight is more than 3000, a sufficiently high bond strengthcannot be obtained when forming the composition.

Specific examples of the epoxy compound are a phthalate diglycidylester, isophthalate diglycidyl ester, terephthalate diglycidyl ester,adipate diglycidyl ester, trimethylolpropane polyglycidyl ether,polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether,butanediol diglycidyl ether, epoxidized soybean oil, epoxidized linseedoil, epoxidized animal oils, epoxidized liquid rubber, epoxidizedsilicone resin, hydrated bisphenol A diglycidyl ether, phenolnovolakpolyglycidyl ether, 4,4'-diglycidyloxy-3,3',5,5'-tetramethylbiphenyl,bis(4-glycidylaminophenyl)methane, isocyanurate triglycidyl. Amongthese, the epoxidized plant (or vegetable) oils are particularlypreferred. These are natural vegetable oils whose unsaturated doublebonds have been epoxidized using for example a peroxide and areavailable commercially as, for example, Asahi Denka Kogyo's O-130P(epoxidized soybean oil), O-180A (epoxidized linseed oil), etc.

Note that the oil which has not been epoxidized or has beeninsufficiently epoxidized, produced as a byproduct when epoxidizing avegetable oil, does not obstruct the gist and nature of the presentinvention in any way. Further, the intermixture of a third componentderived from the natural oil starting material in the composition doesnot pose any problem at all.

Here, an epoxidized vegetable oil means a natural vegetable oil whoseunsaturated double bonds have been epoxidized using, for example, aperoxide. Epoxidized soybean oil, epoxidized olive oil, epoxidizedsafflower oil, epoxidized corn oil, epoxidized linseed oil, etc. may beexemplified.

The amount of the component (B) added in the present invention is 0.01to 5% by weight, based upon the total weight of the component (A) andthe component (B), preferably 0.01 to 0.9% by weight. When the amount ofthe component (B) added is less than 0.01% by weight, there isinsufficient improvement of the bond strength with the substrate, whilewhen more than 5% by weight, the bond strength is improved, but theshaped article gives off an odor or other problems occur, which makesthis unpreferable.

There has been disclosed art in which the epoxy compound used in thepresent invention is used as a stabilizer of polymers such as polyvinylchloride or a plasticizer and, further, is used as a crosslinking agentadded to a polymer compound including a carboxylic acid group orcarboxylic acid derivative group in its molecule (see, for example,Japanese Unexamined Patent Publication (Kokai) No. 60-112815).

It was never anticipated, however, that these epoxy compounds would giverise to an extremely strong effect of improvement of bonding with asubstrate, in particular a substrate composed of polyester, by makingthem into a resin composition by merely blending with a polyethylene,with no polarity, etc.

The reason for the improvement of the adhesion properties is that thepolyolefin is oxidized by the air in the extruder when the polyolefin isbeing melted and formed or while being in contact with the air whenbeing extruded from the T-die etc. It reacts with the epoxy compound inthe process of oxidation, whereby the epoxy compound is first grafted tothe polyethylene and then the unreacted epoxy groups remaining in themolecule of the grafted epoxy compound react with the functional groups(e.g., amino groups, carboxyl groups, carbonyl groups, etc.) of thesubstrate (i.e., member to be bonded).

Epoxidized vegetable oil is particularly effective for a polyester.

Further, it is also possible to add to the composition of the presentinvention, as desired, the usually used additives, for example, aplasticizer, lubricant, various stabilizers, antiblocking agents,antistatic agents, dyes, pigments, various fillers, etc.

In order to obtain the adhesive resin composition of the presentinvention, the above components are mixed by, for example, a Henschelmixer, ribbon mixer, etc. or a mixture is further kneaded using an openroll, Banbury mixer, kneader, extruder, etc. These methods may besuitably used. The kneading temperature is preferably 110 to 350° C.,more preferably is 120 to 300° C. The composition thus obtained may beused for forming a film, sheet, tube, container, etc. by the known meltformation methods or compression formation methods.

The adhesive resin composition of the present invention is excellent inadhesion properties with a substrate, and therefore, is useful as alaminate.

As the substrate, a film or sheet of a polyamide such as polyamide 6,polyamide 66, polyamide 6-66, and polyamide 12, a polyester such aspolyethylene terephthalate and polybutylene terephthalate, or athermoplastic resin such as saponified ethylene-vinyl acetate copolymer(hereinafter referred to as "EVOH"), a resin film on which silica oraluminum has been vacuum deposited, a metal foil such as of iron oraluminum, paper, and other substances generally used as a film or sheetmay be used. The form or shape of the substrate may be any type such asa woven fabric, nonwoven fabric, or sheet.

Among these substrates, the use of a film or sheet of a polyamide orpolyester or aluminum foil is preferable. A polyester film or sheet isparticularly preferable. These substrates may be treated by coronadischarge, flame, preheating, plasma, etc, if desired.

The laminate of the present invention requires that the adhesive resinlayer and the substrate come in contact with each other, but there ofcourse may be another layer on the top of the adhesive resin layer orthe substrate.

In order to form a laminate from the adhesive resin composition of thepresent invention and a substrate, extrusion lamination, co-extrusion,heat sensitive adhesion, calendering, etc. may be used. Particularly,extrusion lamination is preferred in that there is a remarkableimprovement in the bond strength compared with conventional methods.

When producing the laminate of the present invention by the co-extrusionmethod, the resin for the co-extrusion may be for example a polyamide,polyester, EVOH, etc., but the invention is not limited to these.

In the extrusion lamination and co-extrusion, the formation ispreferably performed at a temperature at which the polyolefin isoxidized. The temperature of formation cannot be limited as it isrelated with the speed of formation, but in the case of a polyethyleneresin is generally at least 120° C., preferably 200 to 400° C.,particularly preferably 280 to 340° C. Further, in the case of apolypropylene resin, it is generally at least 170° C., preferably 200 to350° C., particularly preferably 240 to 320° C.

Since, the speed of formation has an effect on the time of residence inthe extruder or the time of contact with air in the molten state, it isrelated to the oxidation of the polyolefin.

Further, in the case of extrusion lamination, formation is possible at alower temperature if an ozone or oxygen treatment is performed. An ozoneor oxygen treatment as used herein means a method for blowing oxygen gasor ozone gas on the resin emerging from the die to effect the surface ofthe resin to oxidize. Further, by the heat treating of the laminateproduced by extrusion lamination at a temperature of 20 to 160° C.,preferably 30 to 80° C., the bond strength can be further improved. Thisheat treatment may be optionally performed, if desired.

It is possible to obtain a laminate made of an inexpensive polyethylenebased adhesive resin composition having good adhesion properties with asubstrate composed of a polyamide or polyester, in particular, by themethod of extrusion lamination, heat sensitive adhesion, andcalendering. Furthermore, the resin composition of the present inventionis superior in adhesion properties with, in particular, a polyester, andtherefore is useful as a laminate.

EXAMPLES

The present invention will now be further illustrated by, but is by nomeans limited to, the following Examples.

Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-7

The values of the physical properties of the Examples 1-1 to 1-11 andthe Comparative Examples 1-1 to 1-7 were measured in accordance with thefollowing methods:

(1) High Speed Formability

This was evaluated by using an extruder of 90 mmφ (50 rpm), a T-diewidth of 750 mm, and an air gap of 120 mm, increasing the take-up speedat the temperature of 300° C., and measuring the speed (m/minute) atwhich the film tears.

(2) Neck-in

This was evaluated by using the above apparatus to form a film of athickness of 20 μm at a take-up speed of 200 m/minute, measuring thewidth of the coat on the substrate, and evaluating the difference withthe die width (mm).

(3) Bond Strength

A laminate film was obtained by using an extruder of 90 mmφ (30 rpm) anda T-die width of 750 mm, using as a substrate a bi-axially orientedpolyamide 6 film or polyethylene terephthalate film, and laminating at apredetermined temperature and a speed of formation of 200 m/minute.

This laminate film was subjected to a moisture absorption treatment(immersed in water at 30° C. for 24 hours) and sampled. The laminatesample was peeled at the boundary between the polyamide 6 or thepolyethylene terephthalate and the laminate coating. The peel strengthat a sample width of 15 mm, a peel speed of 300 mm/minute, and 180°peeling was used as the bond strength.

(4) Odor

A film was formed at a predetermined temperature setting the extruder to90 mmφ (50 rpm) and the T-die width to 750 mm.

The LD4 described below was formed at 300° C. and used as the standardfor comparison of the odor. That is, 100 g of the obtained film waspacked and sealed in a glass bottle. This bottle was heated at 60° C.for 4 hours, then gradually cooled to room temperature and then openedand the contents smelled. Using the odor of the LDPE used as thestandard for comparison, the odors were evaluated in four ranks:

"⊚" better than the odor of LDPE,

"∘" in the case of the same level of odor and posing no practicalproblem,

"Δ" as a slight sharp odor but posing Uo practical problem, and

"×" as a noticeably sharp odor posing a practical problem.

The LDPE used as the standard for comparison of the odor was thefollowing LD4.

As the polyolefin serving as the component (A), the followingpolyethylenes were used:

LD4: LDPE of an MFR of 4.0 g/10 minutes and a density of 0.921 g/cm³

LD19: LDPE of an MFR of 18.7 g/10 minutes and a density of 0.919 g/cm³

LD35: LDPE of an MFR of 35 g/10 minutes and a density of 0.918 g/cm³

As the epoxy-group containing compound serving as the component (B), thefollowing were used:

B-1: Epoxidized soybean oil (O-130P made by Asahi Denka Kogyo K.K.)

B-2: Epoxidized linseed oil (O-180A made by Asahi Denka Kogyo K.K.)

B-3: Phthalate diglycidyl ester

The copolymers used in the comparative examples were as follows:

C-1: Ethylene-glycidyl methacrylate copolymer having a glycidylmethacrylate content of 12% and a number average molecular weight of10,000 (made by high pressure method)

C-2: Ethylene-methacrylate copolymer having a methacrylic acid contentof 8% by weight and an MFR of 8 g/10 minutes (made by Mitsui DupontPolychemical Co., Newcrel 0908C)

Example 1-1

A composition of 99.5% by weight of LD4 and 0.5% by weight of B-1 wasmixed in a Henschel mixer, then was kneaded using a 40 mm singledirection bi-axial extruder at 180° C. to produce an adhesive resincomposition.

Using the obtained adhesive resin composition and, as a substrate, apolyethylene terephthalate film, a laminate was formed by a 90 mmφextruder (30 rpm) at a T-die width of 750 mm, a predeterminedtemperature, and a speed of formation of 200 m/minute to obtain alaminate film.

The results of the evaluation are as shown in Table 1. The compositionwas excellent in high speed formability, neck-in, bond strength, andodor.

Examples 1-2 to 1-11

Adhesive resin compositions were produced in the same way as withExample 1-1 using the compositions shown in Table 1 to obtain laminatefilms. The results of the evaluation are as shown in Table 1. Each wasexcellent in high speed formability, neck-in, bond strength, and odor.

Comparative Example 1-1

A laminate film was obtained in the same way as with Example 1-1 usingonly LD4. The bond strength was low.

Comparative Examples 1-2 to 1-6

Adhesive resin compositions were produced in the same way as withExample 1 using the compositions shown in Table 1 to obtain laminatefilms. The results of the evaluation are as shown in Table 1. Eitherformation was not possible or the high speed formability, neck-in, orodor was poor.

Comparative Example 1-7

An adhesive resin composition was produced in the same way as withExample 1-1 using the composition shown in Table 1 to obtain a laminatefilm. The results of the evaluation are as shown in Table 1. The bondstrength was poor.

                                      TABLE 1                                     __________________________________________________________________________                        Other                Forming                                                                            High speed                      Component (A)                                                                              Component (B)                                                                        components                                                                          Substrate                                                                          Bond strength                                                                           temp.                                                                              formability                                                                         Neck-in                   (wt %)       (wt %) (wt %)                                                                              *1   (g/15 mm)                                                                            Odor                                                                             (° C.)                                                                      (m/min)                                                                             (mm)                                                                              Notes                 __________________________________________________________________________    Ex.                                                                           1-1 LD4 (99.5)                                                                             B-1                                                                              (0.5)                                                                             --    PET film                                                                           Inseparable                                                                          ∘                                                                    310  >200  44                        1-2 LD4 (99.8)                                                                             B-2                                                                              (0.2)                                                                             --    PET film                                                                           900    ∘                                                                    310  >200  42                        1-3 LD4 (99.1)                                                                             B-3                                                                              (0.9)                                                                             --    PET film                                                                           750    ∘                                                                    310  >200  40                        1-4 LD19                                                                              (99.5)                                                                             B-2                                                                              (0.5)                                                                             --    PET film                                                                           870    ⊚                                                                 290  >200  51                        1-5 LD19                                                                              (99.95)                                                                            B-1                                                                              (0.05)                                                                            --    PET film                                                                           650    ∘                                                                    310  >200  54                        1-6 LD4 (98) B-2                                                                              (2) --    PET film                                                                           Inseparable                                                                          Δ                                                                          310  >200  39                        1-7 LD4 (99) B-1                                                                              (1) --    PA6 film                                                                           510    ∘                                                                    310  >200  40                        1-8 mLL1                                                                              (99.4)                                                                             B-1                                                                              (0.6)                                                                             --    PET film                                                                           Inseparable                                                                          ⊚                                                                 280  180   45                        1-9 PP  (88) B-2                                                                              (2) LD4                                                                              (10)                                                                             PET film                                                                           Inseparable                                                                          ⊚                                                                 280  >200  55                        1-10                                                                              LD4 (79) B-1                                                                              (1) C-2                                                                              (20)                                                                             PET film                                                                           Inseparable                                                                          ∘                                                                    300  190   35                        1-11                                                                              LD4 (89.5)                                                                             B-1                                                                              (0.5)                                                                             C-3                                                                              (10)                                                                             PET film                                                                           Inseparable                                                                          ∘                                                                    310  >200  45                        Comp.                                                                         Ex.                                                                           1-1 LD4 (100)                                                                              --     --    PET film                                                                           40     ∘                                                                    310  >200  40                        1-2 LD35                                                                              (99.5)                                                                             B-1                                                                              (0.5)                                                                             --    PET film                                                                           --     -- 310  --    --  Large surging,                                                                unformable            1-3 LD19                                                                              (50) --     C-2                                                                              (50)                                                                             PET film                                                                           120    Δ                                                                          310  120   70                        1-4 LD19                                                                              (50) --     C-1                                                                              (50)                                                                             PET film                                                                           320    x  310  100   68  Bite defects                                                                  at extruder           1-5 LD19                                                                              (90) --     C-1                                                                              (10)                                                                             PET film                                                                           160    x  290  50    66                        1-6 LD4 (94) B-1                                                                              (6) --    PET film                                                                           Inseparable                                                                          x  310  --    --                        1-7 LD4 (99.995)                                                                           B-1                                                                              (0.005)                                                                           --    PET film                                                                           70     ∘                                                                    310  >200  44                        __________________________________________________________________________     *1: PET = polyethylene terephthalate                                          PA6 = polyamide 6 (i.e., Nylon 6)                                        

Examples 2-1 to 2-13 and Comparative Examples 2-1 to 2-12

The MFR was measured based on JIS K6758 under conditions of atemperature of 190° C. for a polyethylene resin and a temperature of230° C. for a polypropylene resin. The bond strength was found bymeasuring the strength (g) when a 15 mm width test specimen was allowedto stand in a constant temperature tank of a temperature of 23° C. and arelative humidity of 50% for 24 hours, then was peeled apart at an angleof 1800 at a speed of 300 mm/minutes. Further, the moist strength wasdetermined by measuring the bond strength by the above method afterallowing the specimen to stand in a constant temperature tank of atemperature of 60° C. and a relative humidity of 90% for 48 hours.

The yarn withdrawal resistance was determined by cutting two warps at acenter portion 70 mm from a short side of the test specimen (20 mm×170mm) and cutting from the two long sides at a location 30 mm from thatposition to the other short side to leave the two warps of the centerportion and cut off the other warps. The test specimen was attached to atensile tester and examined at a tensile speed of 200 mm/minute.

The creep peel test of the bond area was performed by superposing twoshort test specimens of 30 mm width with a 50 mm overlap in thelongitudinal direction and heat bonding the overlapped portion using awelder in a strip of a width of 20 mm. The bonded films were subjectedto a load of 40 kg and allowed to stand in that state at a temperatureof 40° C. for 24 hours after which existence of breakage was determined.

Further, as the component (A), the following six types (A-1 to A-6) ofresins were used:

A-1: ethylene-maleic anhydride copolymer (content of maleic anhydride:2.5 wt %, MFR: 12 g/10 minutes)

A-2: ethylene-maleic anhydride-acrylate terpolymer (MFR: 10 g/10minutes, melting point: 83° C.)

A-3: ethylene-maleic anhydride-acrylate terpolymer (MFR: 12 g/10minutes, melting point: 70° C.)

A-4: ethylene-methacrylate copolymer (Newcrel 0908C: made by MitsuiDupont Chemical Co.)

A-5: ionomer (Himylan H1605; made by Mitsui Dupont Chemical Co.)

A-6: maleic anhydride grafted polypropylene (Adtex ER32OP; made by ShowaDenko)

As the component (B), the following three types (B-1 to B-3) were used:

B-1: epoxidized soybean oil (O-130P; made by Asahi Denka Kogyo)

B-2: epoxidized linseed oil (O-180A; made by Asahi Denka Kogyo)

B-3: epoxy resin material (Epicoat 1001×70; made by Yuka Shell EpoxyCo.)

As the component (C), the following two types (C-1 to C-2) were used:

C-1: low density polyethylene (Showrex L182; made by Showa Denko), MFR:8 g/10 minutes, density: 0.918 g/cm³

C-2: polypropylene (Showaroma LR510; made by Showa Denko), MFR: 14 g/10minutes

Further, as the substrate, a polyester film (12 μm), polyester basecloth (yarn denier: 750 d, count: 20×23/inch³), and polyamide 66 film(15 μm) were used. As the heat sensitive adhesion substrate, a polyestercoated color steel sheet (Yodocolor F1041, made by Yodagawa Steel WorksLtd.) was used.

Examples 2-1 to 2-11 and Comparative Examples 2-1 to 2-10

The components (A), (B), and (C) of the types and amounts shown in Table2 were dry-blended by a Henschel mixer, then the blends were pellatizedusing an extruder (made by Kobe Steel Corporation; KTX-30). The MFRs ofthe resultant pellets were measured.

The pellets were laminated on substrates (polyester film and polyamidefilm) to thicknesses of 25 μm using a 90 mmφ extrusion laminator (madeby Modern Machinery Co.) at a resin temperature of 300° C. and a speedof lamination of 200 mm/minute. For reinforcement in the peeling test,an LLDPE film of a thickness of 60 μm was sandwich laminated. Theresultant films were measured as to the bond strength at the interfacesbetween the resin compositions of the present invention and thesubstrates. The results are shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________            Component (A)                                                                         Component (B)                                                                         Component (C)                                                                            Bond strength (g/15 mm)                               Proportion                                                                            Proportion                                                                            Proportion                                                                            Polyester substrate                                                                      Polyamide substrate                        (parts  (parts  (parts  After                                                                              After After                                                                              After                              Type                                                                             by weight)                                                                         Type                                                                             by weight)                                                                         Type                                                                             by weight)                                                                         MFR                                                                              lamination                                                                         moistening                                                                          lamination                                                                         moistening                 __________________________________________________________________________    Ex. 2-1 A-1                                                                              100  B-1                                                                              1.0  -- --   12.0                                                                             800  810   910  910                        Ex. 2-2 A-1                                                                              100  B-2                                                                              1.0  -- --   11.5                                                                             800  800   850  840                        Ex. 2-3 A-1                                                                              100  B-3                                                                              1.0  -- --   11.0                                                                             750  700   870  840                        Ex. 2-4 A-2                                                                              100  B-2                                                                              1.0  -- --   10.0                                                                             970  950   740  740                        Ex. 2-5 A-1                                                                               70  B-1                                                                              0.5  -- --   11.8                                                                             790  810   810  800                                A-3                                                                               30  B-2                                                                              0.5                                                        Ex. 2-6 A-1                                                                               40  B-1                                                                              0.5  C-1                                                                              60    8.0                                                                             840  860   870  870                                        B-2                                                                              0.5                                                        Ex. 2-7 A-4                                                                              100  B-1                                                                               0.05                                                                              -- --    7.5                                                                             670  670   450  640                        Ex. 2-8 A-1                                                                               40  B-1                                                                              1.0  C-1                                                                              60    8.6                                                                             850  860   780  790                        Ex. 2-9 A-2                                                                               40  B-3                                                                              0.5  C-1                                                                              60    8.8                                                                             810  810   780  760                        Ex. 2-10                                                                              A-5                                                                              100  B-2                                                                              1.0  -- --    4.0                                                                             700  710   540  590                        Ex. 2-11                                                                              A-5                                                                               1   B-2                                                                              1.0  C-2                                                                              65   10.5                                                                             750  780   780  780                                A-6                                                                               34                                                                Comp. Ex. 2-1                                                                         A-1                                                                              100  -- --   -- --   12.5                                                                             380  100   650  680                        Comp. Ex. 2-2                                                                         A-2                                                                              100  -- --   -- --   11.8                                                                             370  120   730  720                        Comp. Ex. 2-3                                                                         A-1                                                                               70  -- --   -- --   12.3                                                                             410  150   780  770                                A-3                                                                               30          -- --                                                 Comp. Ex. 2-4                                                                         A-1                                                                               40  -- --   C-1                                                                              60    9.1                                                                             210   90   650  670                        Comp. Ex. 2-5                                                                         A-4                                                                              100  -- --   -- --    8.0                                                                             200   0    150  600                        Comp. Ex. 2-6                                                                         A-1                                                                               35  -- --   C-1                                                                              60    9.4                                                                             300   90   730  700                                A-4                                                                               5                                                                 Comp. Ex. 2-7                                                                         A-2                                                                               40  -- --   C-1                                                                              60    9.3                                                                             200  110   740  750                        Comp. Ex. 2-8                                                                         A-5                                                                              100  -- --   -- --    5.0                                                                             190   0    170  500                        Comp. Ex. 2-9                                                                         A-5                                                                               1   -- --   C-2                                                                              65   12.1                                                                             250  100   740  730                                A-6                                                                               34                                                                Comp. Ex. 2-10                                                                        A-1                                                                               30  B-1                                                                              20   C-1                                                                              70    8.0                                                                             220  150   100   80                        __________________________________________________________________________

Example 2-12

A polyester base cloth was used as the substrate. A compositioncomprised of 100 parts by weight of the component (A) (A-3) and 1.0 partby weight of the component (B) (B-1) was laminated on the two sides ofthe base cloth to thicknesses of 250 μm by the extrusion laminationmethod. The yarn withdrawal resistance and the strength in the creeppeel test of the bonded area were measured. The results are shown inTable 3.

Comparative Example 2-11

The same procedure was followed as in Example 2-12 to obtain andevaluate a laminate except that just the component (A) (A-3) was used.The results are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                                    Yarn withdrawal                                                               resistance                                                                    (kgf/2 yn)  Creep peel                                            Composition       T-       M-     test of                                     A-3       B-1     direction                                                                              direction                                                                            bonded area                                 ______________________________________                                        Ex. 2-12                                                                             100    1.0     35     40     No breakage                                                                   (95% holding rate)                        Comp.  100    --       6      9     Breaks                                    Ex. 2-11                                                                      ______________________________________                                    

Example 2-13. Comparative Example 2-12

The compositions used in Example 2-12 and Comparative Example 2-11 wereused to prepare films of thicknesses of 75 μm using a T-die moldingmachine. The films were sandwiched between a color plate (25 mm×125 mm,thickness 0.6 mm) and a rockwell of a thickness of 5 mm (Roofnen L; madeby Nittobo Kenkosha), then were placed in a heat sensitive press whilecovered with spacers (thickness 3.5 mm) to prevent crushing, were heatedat just the steel plate side at a temperature of 140° C., and werepressed at a sample facial pressure of 1 kg/cm² for 3 seconds to obtainlaminates. The laminates were separated by hand to evaluate the state ofpeeling under three conditions: initially, after immersion in 60° C.warm water for 1 hour, and after immersion in 60° C. warm water for 4hours.

The result of the evaluation was that the laminate made using thecomposition of Example 2-12 completely ruptured.

On the other hand, the laminate obtained using the composition ofComparative Example 2-11 completely ruptured at the initial stage, butsuffered from interface rupture after immersion in 60° C. warm water for1 hour and exhibited separation over the entire surface of the bondedarea after immersion in 60° C. warm water for 4 hours.

What is claimed is:
 1. A method of extrusion lamination comprising:(1)providing an adhesive resin composition consisting essentially of:(A) atleast one component selected from the group consisting of (i) apolyolefin having a melt flow rate of 0.1 to 30 g/10 min and selectedfrom the group consisting of ethylene homopolymers, propylene polymers,copolymers of ethylene with C₃ -C₁₆ α-olefin and a mixture thereof and(ii) an olefin polymer having at least one functional group selectedfrom the group consisting of a carboxyl group, an amino group, a phenolgroup, a hydroxyl group, a thiol group, an acid anhydride group and acarboxylic acid metal salt group; and (B) an epoxy compound having atleast two epoxy groups in the molecule and having a number averagemolecular weight of 3000 or less, the ratio of the weight of component(B) to the total weight of the components (A) and (B) being 0.01 to 1%,wherein said epoxy compound is:(i) phthalate diglycidyl ester, (ii)isophthalate diglycidyl ester, (iii) terephthalate diglycidyl ester,(iv) adipate diglycidyl ester, (v) trimethylolpropane polyglycidylether, (vi) polyglycerol polyglycidyl ether, (vii) pentaerythritolpolyglycidyl ether, (viii) butanediol diglycidyl ether, (ix) epoxidizedplant oil, (x) epoxidized animal oil, (xi) epoxidized liquid rubber,(xii) epoxidized silicone resin, (xiii) hydrogenated bisphenol Adiglycidyl ether, (xiv) phenolnovolak polyglycidyl ether, (xv)4,4'-diglycidyloxy-3,3',5,5'-tetramethylbiphenyl, (xvi)bis(4-glycidylaminophenyl)methane or (xvii) triglycidyl isocyanurate,and, optionally, (C) one or more additives selected from the groupconsisting of a plasticizer, a lubricant, a stabilizer, an antiblockingagent, an antistatic agent, a dye, a pigment other than a dye and afiller other than a pigment; (2) determining a temperature at which asurface of a film of the polyolefin component (A) is oxidized; and (3)extrusion laminating a substrate with the adhesive resin compositions,at the oxidizing temperature, wherein the surface of the film of thepolyolefin component (A) is oxidized, whereby the epoxy compound (B) isfirst grafted to the compound (A) via a part of the epoxy groups; andthen (4) allowing the unreacted epoxy groups remaining in the graftedepoxy compound (B) to be reacted with the substrate.
 2. A method asclaimed in claim 1, wherein the ratio of the weight of component (A)(ii) to the total amount of the components (A) and (B) is less than 30%.3. A method as claimed in claim 1, wherein the polyolefin (A) (i) is abranched low density polyethylene.
 4. A method as claimed in claim 1,wherein the olefin polymer (A) (ii) has at least one functional groupselected from the group consisting of acid anhydride groups, carboxylgroups and carboxylic acid metal salts in the molecule.
 5. A method asclaimed in claim 1, wherein the olefinic polymer (A) (ii) isethylene-maleic anhydride copolymer or ethylene-maleicanhydride-(meth)acrylic acid copolymer.
 6. A method as claimed in claim1, wherein the epoxy compound is an epoxidized plant oil.
 7. A method asclaimed in claim 1, wherein the ratio of the weight of component (B) tothe total weight of the components (A) and (B) is 0.01 to 0.9%.
 8. Amethod as claimed in claim 1, wherein the oxidation of the film of thecomponent (A) is carried out by a treatment with air, oxygen or ozone ata temperature of at least 120° C. for a polyethylene resin or at atemperature of at least 170° C. for a polypropylene resin.
 9. A methodas claimed in claim 1, wherein the epoxidized plant oil is epoxidizedsoybean oil or epoxidized linseed oil.